U.S. patent number 5,285,619 [Application Number 07/957,596] was granted by the patent office on 1994-02-15 for self tooling, molded electronics packaging.
This patent grant is currently assigned to Williams International Corporation. Invention is credited to Allen M. Jones.
United States Patent |
5,285,619 |
Jones |
February 15, 1994 |
Self tooling, molded electronics packaging
Abstract
A method of protecting an electronic component from the
environment comprising the steps of providing a bag made from
thermoplastic heat shrink material, inserting said electronic
component into said bag, injecting a liquid polymerizable resin
into said bag, heating said bag to shrink it about said electronic
component and said resin, and curing said resin.
Inventors: |
Jones; Allen M. (Novi, MI) |
Assignee: |
Williams International
Corporation (Walled Lake, MI)
|
Family
ID: |
25499818 |
Appl.
No.: |
07/957,596 |
Filed: |
October 6, 1992 |
Current U.S.
Class: |
53/431; 53/442;
53/472; 53/474 |
Current CPC
Class: |
B65B
53/02 (20130101); B65B 55/20 (20130101); B65D
75/002 (20130101); H05K 3/284 (20130101); H05K
9/0043 (20130101); H05K 5/0095 (20130101); H05K
2201/0715 (20130101); H05K 2203/1311 (20130101); H05K
2203/1316 (20130101); H05K 2203/1322 (20130101) |
Current International
Class: |
B65B
55/20 (20060101); B65B 55/00 (20060101); B65B
53/02 (20060101); B65B 53/00 (20060101); B65D
75/00 (20060101); H05K 5/00 (20060101); H05K
13/00 (20060101); H05K 3/28 (20060101); B65B
053/02 (); B65B 031/02 (); B65B 023/00 () |
Field of
Search: |
;53/472,474,442,431,557
;206/328,524 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Coan; James F.
Attorney, Agent or Firm: Lyon; Lyman R.
Claims
I claim:
1. A method of protecting an electronic component from the
environment comprising the steps of
providing a bag made from thermoplastic heat shrink material,
inserting said electronic component into said bag,
injecting a liquid polymerizable resin into said bag,
heating said bag to shrink it about said electronic component and
said resin and thereby exhaust air from within said bag, and curing
said resin.
2. The method of claim 1 including the step of providing a second
bag and coating the surface of one of said bags that is juxtaposed
to the surface of the other of said bags with an electrically
conductive coating.
3. The method of claim 1 wherein said bag and resin are heated
concomitantly to effect shrinking and polymerization thereof,
respectively.
4. The method of claim 1 including the step of coating the exterior
of said bag with an electrically conductive material and placing
said bag in an outer bag of thermoplastic heat shrinkable material.
Description
BACKGROUND OF THE INVENTION
Known methods of packaging electronic components generally entail
enclosing the component in a specially designed container or
encapsulating the components in a rigid media through dipping or
molding. Such high integrity packaging of electronic components,
sometimes termed "potting," often amounts to a disproportionate
share of the weight and cost of the electronic component assembly.
Such known methods have inherent disadvantages, particularly when
electrical shielding is required. Moreover, installation of the
"potted" components generally requires a relatively large volume
allocation.
This situation is ameliorated to some extent by the use of molded
packaging. However, molding requires time intensive steps for
dipping or other application operations. In the case of electronic
components that require grounded shielding for the suppression of
electromagnetic interference, a second coating must be applied to
the outer surface of the molded assembly. Since the vital outer
coating must be protected against damage, additional processing is
generally required to insure the integrity of the shielding.
SUMMARY OF THE INVENTION
The aforesaid problem is solved by a self tooling, multilayered
thermoplastic "shrink wrap" enclosure that is filled with a
prescribed amount of an injectable low viscosity thermoset resin.
Precalculated shrink of the thermoplastic wrap over a measured
amount of thermoset resin results, when the assembly is heated for
shrink and cure, in minimum material usage and in a light weight,
self tooled, rigid assembly. The resulting cured shape of the
molded self tooled assembly will be largely determined by the shape
of the electronic components or mounting therefor. As the wrapping
is exposed to heat and shrinks, it will bridge the high points of
the assembly's components. The final cured shape need not be
governed or altered by subsequent tooling or processing. Conductive
shielding around the electronic components is provided between
layers of the shrink wrap. When heat shrink and cure of the
assembly is completed, the conductive shielding is reliably sealed
internally of the outer plastic coating.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a circuit board having a plurality
of electronic components mounted thereon;
FIG. 2 is a perspective view of the circuit board of FIG. 1
enclosed within a plurality of thermoplastic layers with a resin
injection nozzle extending thereinto;
FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG.
2 after heat shrink of the enclosure and cure of the thermoplastic
resin therein;
FIG. 4 is a cross-sectional view taken substantially along the line
4--4 of FIG. 3; and
FIG. 5 is a view similar to FIG. 3 of the completed shrink wrap
package.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE
INVENTION
As seen in FIG. 1 of the drawing, a circuit board 10 is provided
with a plurality of electronic components 12, 14, 16, 18 and 20
which are secured to the board 10 in the conventional manner.
In accordance With a preferred constructed embodiment of the
instant invention, the circuit board 10 is enclosed in a pair of
plastic bags 22 and 24. It is to be understood that the number of
bags employed is dependent upon the characteristics of the
electronic components and whether the components are required to be
electrically shielded from electromagnetic interference. As seen in
FIG. 4, the outer bag 22 encloses the internal bag 24, which is
provided with an electrically conductive metallic layer 26 suitable
for shielding the components 12, 14, 16, 18 and 20 of the circuit
board 10.
The bags 22 and 24 may be formed as tubes and thereafter heat
sealed along edges 30 and 32 thereof to form an enclosure 34. The
enclosure 34 is provided with an air bleed sprue 36 to provide for
the exhaust of air trapped internally of the enclosure 34 upon the
injection of resin 38 thereinto as well as to provide for exit of
air from the inside of the enclosure 34 upon shrink of the plastic
bags 22 and 24. Resin is injected through a resin injector tube
42.
As best seen in FIG. 5 of the drawing, the portion of the plastic
bags 22 and 24 surrounding a pair of terminals 50 and 52 extending
from the components 16 and 20 are ground away exposing the
terminals 50 and 52 for electrical connection to an electrical
circuit. The shielding layer 24 is provided with a ground terminal
as may be required.
While the preferred embodiment of the invention has been disclosed,
it should be appreciated that the invention is susceptible of
modification without departing from the scope of the following
claims.
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